Automatic drive for dies



Dec.26, 1939. I 2,184,779 4 AUTOMATIC DRIVE FOR DIES Filed Dec. 8, 1937R mm w MM 0 V W fl A J% 0/. E/v rm L Patented Dec. 26, 1939 ticsAUTOMATIC DRIVE FOR. nms

Alfred J. Kiehne, Derby Line, Vt., assignor to Union Twist DrillCompany, Athol, Mass., a" corporation of Massachusetts ApplicationDecember 8, 1937, Serial No. 178,729

2 Claims.

This invention relates to a coupling for driving the spindle of a threadcutting machine from the shaft of the machine.

The common practice is to provide a fixed con- 5 nection between thespindle and the drive shaft of a thread cutting machine, the spindlealways rotating with the shaft. In practice, the carriage of the machineis moved up to the work and the automatic drive for advancing thecarriage and turning the shaft and spindle is set into operation. Therotation of the shaft and spindle ocours in predetermined relation tothe advancing movement of the carriage, the forward feed of the carriagetogether with the rotation of the die operating to cut threads on thework. When the carriage has advanced sufficiently far it is stopped, therotation of the shaft and spindle being stopped at the same time. Thecarriage drive and the drive for the shaft and spindle then are set intooperation in the reverse direction, unscrewing and retracting the diefrom the cut thread. The common practice as last described ischaracterized; first, by inflexibility of the relation between themovement of the carriage and the drive of the spindle in rotation; andsecond, by the location of the control over the movement of the die,both in rotation and in rectilinear movement at the power for drivingthe carriage and for driving the shaft of the machine. Failure tomaintain proper coordination between carriage movement and spindlerotation mutilates the thread being cut. Failure to exercise propercontrol over the carriage feed may cause damage to the stock, to thedie, or to both.

It is an object of this invention to provide a driving connectionbetween the shaft of the machine and the spindle which carries thethread cutting die, the connection operating to provide automaticcontrol, the control originating at the engagement of the die with thethread cut in the stock, of the spindle drive. It is an object toprovide a driving connection from machine shaft to die spindle whichoperates, upon stopping movement of the carriage, automatically todisengage the spindle from the shaft. It is an object to provide adriving connection from machine shaft to die spindle which disassociatesthe carriage advancing movement from the spindle drive so that thecarriage may be stopped and started, at will, without stopping shaftrotation, so long as the directions of carriage movement and shaftrotation are in proper relation. It is an object to provide a drivingconnection between machine shaft and die spindle which so operates thatthe machine shaft may be kept in continuous rotation so long as thecarriage movement, whether continuous or intermittent,is in acorresponding direction, it being necessary only to reverse thedirection of shaft rotation upon reversing the direction of carriagetravel, the driving connection automatically operating to engage and todisengage the spindle relative to the shaft when the carriage movementstarts and stops.

Other objects of the present invention will appear in the followingdetailed description taken in connection with the accompanying drawingin which:

Figure 1 is a side View, partly in elevation and partly in section,illustrating a drive connection, typical of this invention, incombination With the machine shaft, spindle, and die.

Figure 2 is a cross sectional view taken on line 2-2 of Figure 1.

Figure 3 is a side view, partly in elevation and partly in section,illustrating another typical drive connection of this invention, incombination with shaft and spindle.

Figure 4 is a cross sectional view taken on line i-l of Figure 3. i

Figure 5 is a view similar to that of Figure 3, showing a modificationof the invention.

This invention is concerned with the driving connection, shown inFigures 1 to 4 of the drawing, which operates automatically to connectand to disconnect the spindle, for a thread cutting die, to and from thedrive shaft of a machine. In Figure l, ahollow drive shaft is indicatedat l. The shaft 1 is mounted for rotation in a suitable carriage (notshown), conventional to such machines. The shaft l is driven in rotationfrom a suitable source of power and by suitable driving connections,which are conventional and there-' available for effecting a controlaction, is in the a direction of the spindle axis, which movement arisesby the screwing and unscrewing of the die on the cut thread. To make useof such an axial control movement, the spindle 4 is mounted It iscal forsliding movement in an axial direction, relative to the shaft I.

The shaft I has a bore 4 into which the end 6 of the spindle extendswith close sliding and running fit. The shaft I carries a cylindricalhousing 1, open at one end. A collar 8 is mounted in the open end of thehousing I and is secured in place by screws 9. The collar 8 has a boreII] in which the spindle 4 has a close sliding and running fit. The lastdescribed structure affords support for the spindle 4 from the shaftwhile permitting relative movement between the shaft and the spindleeither in axial reciprocation or in rotation.

According to this invention, the driving connection is such as to afforda forward drive to cut threads, a reverse drive to retract the die fromthe cut thread, and a neutral position where the die and spindle aredis'associated from the driving power afforded by the rotating shaft.Those actions are to be under the control of the engagement between thedie and the stock. Structure for performing those functions is describednext.

The spindle 4 is provided with a hub I I, which is in fixed drivingconnection with the spindle. A track I2 extends circuferentially aroundthe hub II, the track I2 being substantially semicircular in profile, toengage with a ball I3. The ball I3 has rolling engagement with the trackI2. The ball I3 is supported in a spherical seat I4, formed in the screwI5, which is threaded into a bore I6, through the wall of the housing I.

The track I2 affords the neutral position of engagement with the balll3. So long as the ball is engaged with the track I2, the shaft I mayrotate without driving the spindle 4, the spindle 4 being held fromrotation by engagement of the die 2 with a thread being cut.

The hub II is provided with recesses I! in the flange I8. The flange I8extends circumferentially around the hub at one side of the track I2.The recesses I! are of any suitable shape adapted to receive the ball I3in driving engagement with the face of the recesses. When the spindle 4is displaced, relative to the housing 'I and shaft I, in a right handdirection from the position shown in Figure l, the ball I3 is broughtinto engagement with a recess I'I. Power from the shaft I, for drivingthe spindle 4 in rotation, is transmitted through the housing 1, ballI3, and flange I8 with which the ball I3 is in engagement.

The hub II has another flange III which extends circumferentially aroundthe hub at the side of the track I2 distant from flange l8. The flangeI9 has recesses 20 of a suitable shape and size to engage with the ballI3. When the spindle 4 is displaced relative to the housing I and shaftI, to the left from the position shown in Figure 1, the ball I3 engageswith the flange I9 at one or another of the recesses 28. This engagementserves to transmit power from the rotating shaft I to the spindle 4 anddie 2.

The operation of the device illustrated in Figures 1 and 2 is describednext. The carriage, in which the shaft I is mounted for rotation, ismoved toward stock on which a thread is to be cut. The movement of thecarriage up to the stock usually is by hand. The spindle 4 may or maynot be rotating as the carriage is moved up to the stock. The spring 2|between the collar 8 and the hub II, which spring is not essential tothe invention, tends to thrust the spindle 4 to a position where theball l3 engages with the flange I8. In such case, the spindle 4 with die2 is carried in rotation with the shaft I if the shaft be rotating asthe carriage is moved up to the stock. So far as the practice of thisinvention is concerned, the ball I3 may be in engagement with the trackI2 during movement of the carriage up to the stock.

When the die is in proximity to the stock, the machine drive, foradvancing the carriage to out the thread, is set into operation. The dieis moved into engagement with the stock. If the ball I3 is in engagementwith the flange I8 by operation of spring 2|, at the time when the diefirst engages the stock, the drive connection from the shaft I to thespindle 4 is complete and the thread cutting operation proceeds in awell known manner. If the ball I3 is in engagement with the track I2 atthe time when the die first engages with the stock, the first effect isthat the advancing movement of the carriage thrusts the ball I3 towardthe flange I8 and causes it to engage into a slot II, the spindle 4being held, at that time, by engagement of the die with the stock. Assoon as the ball I3 has established .a driving connection with theflange I8, by the last described action, the thread cutting operationproceeds in the usual manner.

When the carriage has advanced to the point where the thread is cut asfar as desired,.the advancing movement of the carriage is stoppedmanually or automatically. The shaft I may continue to rotate when thecarriage is stopped, and continued rotation of the die 2, in threadcutting direction, ensues. Since the spindle 4 is free to slide axiallyrelative to the shaft I, the die 2 climbs up the thread, which has beencut in the stock, thereby pulling the spindle 4 to the left, as viewedin Figure 1, relative to the shaft I and hub I. This movement proceedsuntil the huh I I has been moved sufliciently far to disengage theflange I8 from the ball I3. When that disengagement is complete,rotation of the spindle 4 and the die 2, which is resisted by the stock,ceases, although rotation of the shaft I may continue.

When it is desired to retract the die 2'f1'om the cut thread, therotation of the shaft I is reversed in direction. The ball I3 is engagedwith the track I2 at the time when the rotation of shaft I is reversed.Next, at any convenient time, sub-sequent to or coincident with thereversal of direction of rotation of shaft I, the drive for the carriageis set into operation to move the carriage in reverse direction awayfrom the stock. The first effect of the carriage movement is to shiftthe shaft I to the right as viewed in Figure 1 relative to the spindle4, which is held stationary by engagement of the die with the stock. Theshifting movement brings the ball I3 into engagement with one or anotherof the slots 20 in the flange I9 to establish a driving connectionbetween the shaft I and the spindle 4. When this driving connection hasbeen established, the movement of the die 2, both in rotation andretraction, takes place in the conventional manner for unscrewing thedie from the cut thread. Once the die is free from the cut thread, thetendency of the drive connection is for the hub II to find that positionWhere the ball I3 rides in track I2.. The spring 2I, if present, biasesthe spindle I4 to a position where the ball I3 engages with flange I 8,preparatory to the next following thread cutting operation.

Figures 3 and 4 show a drive connection between machine shaft and diespindle which has the same operating characteristics as the device shownin Figure 1 and 2 and described above. The structural differencesbetween the devices of Figures 1 and 3 are only those essential tooperating convenience as determined by the size of the operating parts.

In Figure 3, the machine shaft is shown at 22, a housing 23 being fixedonto the shaft. The spindle 24 has bearing support in the housing 23 andcarries the conventional die 25, in cage 2% The spindle 2% has a-stem 21which extends into the hollow shaft 22. A spring 28 engages with thehead 29 of stem 21, and with a shoulder 39 formed within the bore ofshaft 22. The spindle 25 is provided with a circumferentially extendingtrack 3 l there being shoulders 32 and 33 at opposite sides of the track3!. Recesses 34 and 35 are provided in the shoulders 32 andrespectively. A ball 36 is supported in a spherical seat 31, in nut 38,threaded into a bore through the wall of housing 23.

The ball 35 may ride in the track 3i with rolling engagement, or it mayengage either shoulder 32 or shoulder 33, at a recess 34 or a recess 35.Although there are some differences in structure between the two formsof invention shown, it is believed that the equivalence of the variouselements of the device, shown in Figure 3, with the elements shown indevice of Figure 1 will be apparent. The mode of operation of the deviceshown in Figure 3 is the same as that for the device shown in Figure l,as will be apparent to one skilled in the art. I

The modification shown in Figure differs from that of Figure 3 in theshape of the recesses iii, as compared with the recesses 35. Therecesses flil are made with sloping faces ti so that no drivingengagement may occur between such faces and the ball 42. Drivingengagement may occur only between faces 43 and the ball 42. The effectof sloping faces ll is to provide a rachet-like drive.

The operation of the device of Figure 5 is like that of Figure 3 exceptthat, if ball :32 be in engagement with the recess 4%, opposite to thatin which driving connection should occur, the effect of the slopingfaces 4| would be to move the driving connection relative to the shaftso as to bring the ball into engagement with the other recess.

The invention has been described in detail by way of illustration. It isnot intended so to limit the invention. Variations in the details ofconstruction may be made, as will be apparent to one skilled in the art,without departing from the scope of the invention as defined in thefollowing lclaims.

What I claim as my invention is as follows:

1. An automatic drive including a hollow shaft, and a spindle, one endof the spindle being arranged in the hollow shaft, there being runningand sliding engagement between the shaft and spindle to afford supportfor the spindle; the spindle being rotatable with the shaft, rotatablerelative to the shaft, and reciprocable relative to the shaft; the otherend of the spindle projecting .from the shaft and being adapted to mounta thread cutting die, a driving means fixed to the shaft and includinga'ball seated on the shaft to roll freely, a driven means fixed to thespindle and located within the hollow shaft, said driven means includingan annular track concentric with the axis of rotation and shaped forfreely rolling engagement with the ball, said driven means including ashoulder at each side of the track, there being slots in the shouldersopening into the track and adapted to receive the ball in engagementwith a shoulder, the driving means and driven means being relativelyreciprocable by relative reciprocation of the shaft and spindle to shiftbetween ball-and-track engagement and ball-and-recess engagement; saidshaft, spindle, driving means and driven means being free for relativereciprocation to effect driving connection and dis-connection under thecontrol of the action of the thread cutting die on the stock togetherwith movement of the shaft in rotation and in axial direction relativeto the stock.

2. An automatic drive including a hollow shaft, and a spindle, one endof the spindle being arranged in the hollow shaft, there being runningand sliding engagement between the shaft and spindle to afiord supportfor the spindle; the spindle being rotatable with the shaft, rotatablerelative to the shaft, and reciprocable relative to the shaft; the otherend of the spindle projecting from the shaft and being adapted to mounta thread cutting die, a driving means fixed to the shaft and including aball seated on the shaft to roll freely, a driven means fixed to thespindle and located within the hoilowshaft, said driven means includingan annular track concentric with the axis of rotation and shaped forfreely rolling engagement with the ball, said driven means including ashoulder at each side of the track, there being slots in the shouldersopening into the tracl: and adapted to receive the ball in engagementwith a shoulder, the driving means and driven means being relativelyreciprocable by relative reciprocation of the shaft and spindle to shiftbetween ball-and-track engagement and ball-and-recess engagement; saidshaft, spindle, driving means and driven means being free for relativereciprocation to effect driving connection and dis-connection under thecontrol of the action of the thread cutting die on the stock togetherwith movement of the shaft in rotation and in 1 axial direction relativeto the stock, a spring

